Audio Video Switch: This is an 8-input x-output audio/video switch module to be controlled from a computer, for example from the parallel port. Each audio/video output can be switched to any of the 8 inputs, separately.1-module drives1-audio/video output and has a34-pin connector to plug into the system interface. You can use video OPA-s on the4051 output instead. Note that you can get full integrated video multiplexers from Maxim.

Circuit Adapts Differential Input to Drive Coax: 05/08/97 EDN-Design Ideas / Uses an HFA1100 or HFA1105 to convert a balanced input signal to a single-ended output signal, uses positive feedback to characteristic-impedance matching while increasing the available output swing, as compared with using a simple series termination resistor.

Circuit allows accurate sync of multiple CCTV signals: 10/23/97 Electronic Design - Ideas for Design / There are times when CCTV
sync signals must maintain temporal fidelity
when derived from composite video. One such
case involves applications in which several
video sources are polled by an instrument
which then extracts photometric data from
video.

Circuit Facilitates Video Fading: 03/15/01 EDN-Design Ideas / PDF contains multiple circuits - scroll to find the one of interest / Turning potentiometer P1 adjusts the image brightness from normal video to a black image. With the P2 potentiometer ganged to P1, the sound also varies accordingly. The objectives in building this circuit are to use inexpensive, readily available components and to obtain operation without a battery.

Closed Caption Decoder: This is a closed-caption decoder with serial output, based on a PIC16C71, an Élantec EL4581C sync separator, and an LM393 dual comparator (for data slicing with automatic threshold).

Color Bar Generator

Color Video Travels on twisted Pair Cable: 08/17/95 EDN-Design Ideas / This circuit transmits video anywhere phone lines exist. Although the circuit has more electronic components than the traditional single amplifier used to drive a coax cable, you can easily justify the additional electronics required to drive twisted-pair cables.

Trigger Circuit Locks onto one Horizontal Line: 09/02/96 EDN-Design Ideas / Produces an oscilloscope trigger that synchronizes the horizontal sweep to a video signal that allows you to view any horizontal line by adjusting a potentiometer

TV REMOTE JAMMER: Just point this small device at the TV and the remote gets jammed. The circuit is self-explanatory. 555 are wired as an astable multivibrator for a frequency of nearly 38kHz.

Video Circuit Clamps under All Conditions: 4/23/98 EDN-Design Ideas / Many video-circuit Clamps operate well in the presence of a composite-video signal but cannot achieve a Clamp level with signals other than composite video or in the absence of an input signal. This circuit, developed for the ADC1175 (a popular and inexpensive, high-performance, 8-bit, 20M-sample/sec ADC), provides the normal back-porch Clamp function to the input of the ADC in the presence of a composite-video signal. The circuit further ensures that the voltage presented to the ADC is within its correct operating range in the absence of an input signal and forces any signal other than composite video to be within the ADCs input common-mode range.

Video Distribution Amplifier: This is a useful circuit for amplifying and distribution of video signals. This circuit takes normal composite video signal and outputs it to up to3-monitors.

Video Effects Unit: unit provides various wipe patterns for use when video dubbing, wipes1-signal to black, it does not provide mixing between two separate input signals.

Video emitter uses battery power:
08/30/2001 EDN - Design Ideas / The block
diagram in Figure 1 shows how to make a
cable-free, direct-video system. The system
allows users to walk from booth to booth at
an exhibition to interview people and to
display the interviews in real time on three
screens at key locations. You can use the
small and simple system each time you need
to capture image and sound on the run.

Video monitor adapter enhances oscilloscope:
08/18/97 Electronic Design - Ideas for
Design / Video signals can be difficult to
display on an oscilloscope. Normal trigger
circuits in most oscilloscopes have trouble
getting a stable trigger from the combined
vertical and horizontal sync signals, color
burst, and picture signal in a composite.

Video multiplexer uses high speed op amps: 08/21/03 EDN-Design Ideas / Video multiplexers route video from several sources to a single channel. Low-end consumer products use CMOS analog switches and multiplexers, such as the 4066 and 4051. Unfortunately, these devices have a series on-resistance that ranges from approximately 100Ω to 1 kΩ,
a resistance that is not constant with video
level and that appears in series with the
signal.

Video Switch: This article (published in Circuit Cellar Magazine) describes a circuit which switches RGB signals between two genlocked cameras. This project used analogue switched and programmable logic (programmed using VHDL). This article is also available in PDF format and in zipped packet from Circuit Cellar Apr1999.